Twenty-two years ago Li Peng Monroe and her then husband, were having trouble getting pregnant. Like many couples with fertility problems, they turned to in vitro fertilisation (IVF).

"It's not an easy process to go through ??? the probability of falling pregnant was quite low back then through IVF, for me certainly," Ms Monroe, 51, said.

"There's a perception that fresh is better so you start with the fresh ones, and then if the fresh ones don't take, you've got embryos that are frozen that you can use," she said.

It was her frozen embryos that gifted her two daughters, Melissa, now 20 years old, and Ashley, 17. Frozen embryo transfer has come a long way in the past few years.

A new study now gives couples trying IVF peace of mind whichever method they choose, showing both fresh and frozen embryo transfers offer an equal chance of having a child.

In women without polycystic ovaries, the pregnancy rates and live births were comparable when implanted with either fresh or frozen embryos, according to the study published in The New England Journal of Medicine on Thursday.

Rates of ongoing pregnancy occurred in 36 per cent of the frozen-embryo group and 34.5 per cent in the fresh-embryo group, according to the study.

Live births were recorded in 33.8 per cent of the frozen-embryo group and 31.5 per cent of women in the fresh-embryo group.

The study included almost 800 couples undertaking IVF in Vietnam, who received either fresh or frozen embryo transfers on a randomised basis and was completed in under a year.

Michael Chapman, Professor of Obstetrics and Gynaecology at UNSW and President of the Fertility Society of Australia - who was not involved in the study - said the slight percentage difference in groups is not significant.

"Even with 800 odd patients in the study ... [frozen-embryo transfer] may turn out to give an extra one or two pregnancies," Professor Chapman, who is also a consultant at IVF Australia, said.

"It's good that [clinicians] will be able to advise patients that frozen-embryo transfer is as good as fresh, because historically frozen has not been as good."

Co-author Ben Mol, Professor of Obstetrics and Gynaecology at the University of Adelaide's Robinson Research Institute, said the study was done after the development of a 'quick-freeze' vitrification method in recent years resulted in an increased uptake of frozen-embryo transfers.

But the study suggests it may not increase the chances of a live birth compared to fresh embryos in the study population.

"There are many examples in medical history where people jump to innovation and new things, and then after a while it turns out that the new thing is not necessarily so much better," Professor Mol said.

Previous research conducted on women undergoing IVF with infertility problems linked to polycystic ovary syndrome (PCOS), found frozen-embryo transfer led to more live births.

But until now, it was not known whether this was also the case for women confronted with fertility problems due to other reasons.

Professor Mol said going down the path of frozen-embryo transfer can come at a cost.

"It's not a lot, but it's a couple of hundred of dollars that you're talking about, so obviously that could be part of the choice [for patients]," he said.

"The other thing is that people want to have their baby as soon as possible, and frozen transfer means a delay of at least one month, so there are arguments for fresh transfer."

Professor Chapman said one limitation of the study was applying the results to Australia.

"They only looked at day-three embryos, whereas the general practice in Australia today is day-five transfers," he said.

But the research was the first of its kind to study fresh versus frozen-embryo transfers in such a large number of non-PCOS patients.

"It's fantastic that Australian researchers are collaborating with other countries to get high class research coming out of Asia," Professor Chapman said.

"Health systems in other countries make it more possible to do proper randomised control trials, so it's excellent that we are getting those relationships built up."